Aircraft fuselage and wing construction



M. WATTER ETAL AIRCRAFT FUsELAGE AND wINGcoNsTRUCTIoN Feb. 18, 1947.

.Filed June 28, 194s 14 sheets-sheer \I I I I Il; E I I I 59 I I I I I I I I I I I I l I I I I I I I I I I I INVENTORS M1. chclel Waiter lbert G. Dean.

lA TTORNE Y Feb. 18, 1947.

N V TORS Michael Waiter :HLEDQF Cv. Decm. I BY 10- Tg4/W ATTORNEY V Feb. 18, 1947. M, wATTER ETAL AIRCRAFT FUsELAsE Ann WING. cousTnucT'Ion A Fiied June 28V, 1943 14 Sheets-$11991'I 4 INVENTORS Mnhaei Waiter. mbart G. Dean.

9% P Y ATT ,IPN

TAL? ORNE;l

Feb 18 1947 INVENTORSV M ha LW iff.

QlbeCrDeanf ATTORNEY 14Sh t Sh t6 By Wm To ir Y ` i annum"mmumnmnmun lIl Feb. 1s, 1947. M, WATTER mL 2,416,245

AIRCRAFT FUSELAGE AND WING l Mtlnilliimmiim l j I INVENTUMA v Mldmel Wai: te?. `Gibert G. Dean ATT RNEY Feb. 18, 1947. M WATTER TAL 2,416,245

AIRCRAFT FUSELAGE ND WING CONSTRUCTION Filed June 28, 194:5 14 sheets-sheet a FIG@ On Fles 1&2

N VEN TORS Michal Wattex.

BY P .ATTORNEY Gibert G. Dean.

Feb- 18, l947- 'M.WATTER Eru.A

AIRCRAFT FUSELAGE AND WING' CONSTRUCTION Filed .June 28, 1943 -14 sheets-sheet 9 FIGO on Flcf's. 10:94@`

FIL@ M On FIGS l-L 46 Michael WQQE I A TTORNE Y Feb; A18, 1947. M, lWATIrER ETAL, 2,416,245

l" AIRCRAFT FUSELAGE AND WING coNsTRUcT-1oN Filed June 2.8; 1945 14 Sheets-Sheet 10 man (On F1654 'LM (On Flcfifl.)

illlllllllll It l ,www lllllllllllllllllllllli Il IIIIHIIIII Mw@ waiter.

Y Ww PTM LW ATTORNEY v 'embark @Dean Feb. 18, 1947.

M. wA'rTER ETAL AIRCRAFT FUSELAGE AND WING CONSTRUCTION Filed June 2e, 194:5 14 sheets-sheet 11 FIIGALS (Gamesa-041414) INVENTUM NULHCLQL watten 1116.16 On FIG'sAo-u-) m. m w

if. .Y B

Feb. is, 1947.

M. WATTER AL AIRCRAFT FUSELAGE AND WING CONSTRUCTION 14 Sheets-Sheet 12 Filed June 28, 1945 @TENUE Ov (NVENTORS' Midmel Waer l @wert G: Dean ATTORNEY L M. wATTER Er AL 2,416,245

AIRCRAFT FUSELAGE AND WING CONSTRUCTION Feb. 18, 1947.

14 Sheets-Sheet 13 l Filed June 28, 1943 FIIGJZS (On. FIGLI.)

P11651 (On FIG u) FIGX?. (Om FIG 11) @IberkGaDean BY WMP ATTORNEY Flg. (On :2165.40.28)

Feb. `18, 1947. M. wATTER ETAL 2,416,245

' AIRCRAFT FUSELAGE AND WING CONSTRUCTION Filed June `28, 1943 14 Sheets-Sheet-l4 NENTORS C Michael Waiter,

' Qlberjc CT.' Dean.

ABY 1 v v ATTZRNE) yPatented Feb. 18, 1947 AIRCRAFT FUSELAGE AND WING CONSTRUCTION Michael Watter,. Philadelphia,V and Albert G. Dean, Narberth, Pa., assignors to The Budd Company, Philadelphia, Pa., a corporation of Pennsylvania Application June 28, 1943, Serial No. 492,494

12 Claims.

This invention relates to aircraft, particularly to airfoil-to-body connections therefor, and has for an object the provision of improvements in this art. The invention is especially designed to provide sturdy connections between the wings and body or fuselage of an airplane while preserving the maximum clear space within the body for cargo.

One of the particular objects oi the invention is to provide a strongr body compartment structure which is adapted to anchor the wings.

Another object is to provide a structure which furnishes a very rigid wing support. y

Another objectI is to provide quick assembly of the Wings to the body.

Another object is to provide a wing structure which is adapted to transmit stresses from a secondary stress region of the body to a primary stress region to compensate for weakening the body as by a side opening in a secondary stress region.

Another object is to provide a joint between a body and an airfoil which utilizes the wing spars and reinforced skin'blankets in an advantageous manner in making the connections.

Another'object is to provide a wing-body joint which can be conveniently and eiectively connected, particularly by spot welding methods, at least in large part. f

Another object is to provide a body bulkhead unit adapted to carry the wings which is composed of a plurality of skin-reinforced bulkhead elements.

Another object is to provide a wing and body construction formed entirely or substantially of sheet metal, cold-rolled stainless steel being the metal especially contemplated herein.

The above-mentionedvand other objects of the invention will be apparent from the following de-r scription of an exemplary embodiment, thereof which is illustrated in the accompanying drawings, wherein:

Fig. 1 is a side elevation of the central portion of an airplane which embodies the present invention; i

Fig. 2 is a plan view of the same, the left wing and certain fairing strips being shown in preassembly relationship;

Fig. 3 is a partial side elevation of the fuselage without the wing;`

Fig. 4 is an enlarged side-top-rear perspective View of the primary wing attachment zone shown in Fig. 3;

Fig. 5 is a similar perspective View with the wing attached and parts cut away;

Fig. 6 is a similar perspective view of a smaller area after additional fairing strips have been attached;

Fig. 7 is an inside side-front perspective view of a portion of the primary wing attachment zone, parts being cut away to reveal sectional structure;

Fig. 8 is an inside side-rear perspective View of a portion of the primary wing attachment zone, the view being taken in an intermediate portion of this zone;

Fig. 9 is a vertical transverse rearward-lookingthe View being taken on the line 12-12 of Figs.

1,- 2 and 3;

Fig. v13 is a partial enlarged horizontal section taken on the line I3-I3 of Fig. 12; 1

Fig. 14 is a partial enlarged vertical section taken on the line |4944 of Fig. 12; i

Fig'. l5 is an enlarged partial vertical chordwise section taken on the line I5-l5 of Fig. 2, the section also being indicated on Figs. 10, 1l, 12 and 16 Fig.Y 16 isa horizontal section taken on the line iii- I6 of Fig. 15, the section also being indicated on Figs. 10 and 11; A

Fig. 17 is a fragmentary lenlarged horizontal section of parts shown in the area Il of Fig. 16;

Fig. 18 is a vertical section taken on the line |8l8 of Fig. 17;

Fig. 19 is a section taken on the line Ill-i9 of Figs. 17 and 18;

Fig. 20 isa section taken on Figs. 17 and 18;

Fig. 21 is a fragmentary enlarged horizontal section of parts shown in the area 2| of Fig.`16;

Fig. 22 is a vertical section taken on the line 22-22of Fig. 21;

Fig. 23 is a section taken on the line 23-23 of Figs. 21 and 22;

Fig. 24 is a section takenon the line 2i24 of Figs. 21 and 22;

Fig. 25 is an enlarged horizontal section taken on the line 25-25 of Fig. 11;

the line 20-20 of 3 Fig. 26 is an enlarged vertical section taken on theV line -26 of Fig. ll, the section also being indicated on Fig. 25;

Fig. 2'7'is an enlarged vertical section taken on the line 21-21 of Fig. 1l, the section also being indicated on Fig. 25;

.Fig 28 is an enlarged horizontal section takenI on the line 28-28 of Fig. 10;

Fig. 29 is an enlarged vertical section taken` on the line 253-29 of Fig. 10, the section also being indicated on'Fig. 28; f Y

Fig. 30 is an enlarged vertical section taken on the line Sil-3d of Fig.v 10, the section also being indicated on Fig. 28;

Fig. 31 is an enlarged horizontal section taken,V

on the line Sl-S! ofFig'. l1;`

Fig. 32 is an enlarged horizontal section taken on the line 32-32 of Fig. l1;

Fig. 33 is an enlarged horizontal section taken] on the line 33-33 of Fig. 10

Fig. 34 is an enlarged horizontal section taken on the lineS-M of Fig. 10;

Fig. 35 (on Sheet 3) is an enlarged partial in- Generalvr arrangement Although the invention has wide applications, it has especial advantages in connection with airplane wing-to-fuselage joints, particularly in connection with cargo planes having clear compartment space between the wing roots and having a door opening on oneor both sides beneath the wing, and so will be specifically described in this' connection. .Y

The iioor of a cargo body must be built to withstand heavy loadings; hence theriioor girders or beams are made correspondingly strong. The

body requires ygreat rigidity, particularly in thatl portion of its length which is supported by the favorable.

wings; hence the side walls are Hreinforced by bulkhead elements and the roof girders or beams are made suiiicientlyr strong to take the required compression loads. lSuch a 'bodyr construction is' strong enough and rigid enough to furnish an efdcientanchorage for the wings; hence the wings are anchored to the body bulkhead Sides, thus avoiding the necessity for providing additional weight-adding structures for the wingr anchorages, as for example the necessity for providing through-running wing spars, either in the vCargo compartment, where '.Athey would Yobstruct .the` space, or outside-the body, where they would` largely impose parasitic drag.

The airplane illustrated hereinris of the high` tion and narrower toward the lower end where it connects with the oor girders. In vertical spanwise section the side of the bulkhead unit is Vtriangular, the interior side being vertical.

The floor girders are made deep in the center for cargo load carrying strength, the upper `or vinside chord of the girder being straight and the lower chord being convex. When the airplane 'A is in flight the lower chord tends to straighten in tension, due to the cantilever action of the wings and bulkhead units, and the iloor girders tend to bend upward at the center due to air pressure, but this bending tendency is opposed by the weight of the cargo on the iloor. Consequently, the loading factors compensate and provide a favorable stress resultant in the floor girders. The in-ight resultant on the roof girders is equally The cantilever action of the wings compresses the roof girders and tends to `bend them downward in the center; but the air above exerts a lifting action tending to restore the girders to straight' condition. In consequence', the body box section shape is substantially maintained and the up-bending effect on the wings is kept at a minimum.

In landing, the motors mounted on the leading edge of the wings outboard from the body and forward of the main landing wheels, impose heavy shear stresses in the wing-to-body anchorages. The structure disclosed herein is well adapted to withstand these shearing stresses as well as the other stresses which 'must be taken. Also in landing, since the main supporting wheels are located beneath the motor nacelles, the body imposes heavy shear on the wing anchorages.

In'landing, also, the overhanging tail of the body together` with cargo stored behind the landing gear exerts a bending moment on the body near the landing gearzone. This tends to flatten the body vertically in the region of the door which in turn tends to cause the body to bulge here. AThe wing structure is so formed and arranged as to resist this tendency to bulge. Specically, the wing ro-ot and body structure forms a kind of C-unit, viewed horizontally, which is strong in the primary stress zone through the body bulkheads to resist bulging in the weak secondary stress zone in the region of the door.

The primary stress Zone of the body coincides with the primary stress zone yof the wings. Specifically, the body comprises a bulkhead unit cornposed of five connected bulkheads, two of which, fore and aft, are "connected to the rfore and aft spars ofthe wing and three of which, intermedi- Vately, are connected to the heavy, Stringer-reinforced skin blankets of the wings.

The wings are provided withprojecting shear coupling members, and during assembly are mov-ed endwise until these coupling members are telescoped with the bulkheads, after which the connections are made. The connections are made in'large part by spot'welding operations, the parts being accessible for welding tools from inside the body and from the door or doors. Alternatively, the bulkhead sides may be pre-assembled with the wingsand later attached to the top and bottom assemblies.

Thereafter the fairing or closure pieces are assembled.

General arrangement by reference to the drawings Y As shown in Figs. 1 and 2, the airplane here illustrated comprises a cargo body A and wings B. The right wing in Fig. 2 is shown in assembled position and the left wing is shown in pre-assern bly position with some of the top fairing pieces located between the body and wing.

The wing comprises a leading or nose section do, a main load-carrying section lill, and a trailing section 56. A forward spar l anda rear spar 42 are integral parts of the main wing section 40. The wings, or at least the inner panels thereof if they are formed of a plurality of panels as preferred, are completely formed as separate subassemblies before they are brought to the body for attachment. Theirroot ends are adapted to be telescoped into the sides of the body by endwise, i. e., spanwise, movement; after which they are attached.

In the region of the trailing section of the wings the body is provided with an opening C in one or both sides, both in the preesnt case. In the present instance also the opening is a door for the passage of cargo, either personnel, equipment, or supplies.

As shown in Fig. 2, the body comprises a plurality of transverse girdle frames, most of them 59 being light and formed with generally rectangular interior compartment openings and those in the major stress zone being very strong and comprising bulkheads 60 which are made deep spanwise on the sides and formed with a more nearly exact rectangular interior opening. The bulkheads from front to rear, are designated as D, E, F, G and H.

Body and bulkheads A section at the front bulkhead is shown in Fig. 9. Here it may be seen that the two deep sides of the forward bulkhead D are connected at the upper end to a roof girder or beam and at the bottom to a floor girder or beam 62. The connection to the roof beam is made through strong gussets 63 and the connection to the floor beam is made through projections of the iioor beam web 64 and by mating iianged longerons 05.

In addition to the web 64, the floor beam 62 comprises chords S6 and S1 and Vertical stiifener ribs 68. The iioo-r beams 62 are covered interiorly by a floor 09 and exteriorly by a Stringer-reinforced skin blanket 10. The roof is covered by a Stringer-reinforced skin blanket 1 I. The side edges of the roof skin blanket 1| are reinforced by angle-shaped edge stiffene'rs or longerons 12. At the front and rear portions of the heavy stress Zone a skin tie-in member 13 is welded to the longerons 12.

Each bulkhead side comprises a triangular web 15, converging chords 16, 10a, horizontal stiiener ribs 11 on the lower portion below the wing, and vertical stiffener ribs 18 and transverse plates 19, Fig. '1, on the upper portion within the wing zone. The construction of theupper portion of the forward bulkhead D and the next adjacent bulkheads E and F is shown in enlargement in Fig. '1. As seen in the broken section T in Fig. '1 and in Figs. 16, 25y and 28, the inner chord 16 comprises two angle elements 80, one welded on each side of the web, and a cap strip 8|. As seen in the broken section W of Fig. '1, and in Figs. 16, 31, 32, 33 and 34, the outer chord 16a comprises a plurality (three shown) of nested angle members 82 welded to the inclined outer edge of the bulkhead web 15. For the fore and aft bulkheads D and H which are to beconnected to the wing spar elements the side edge of the angle members may be left extending beyond the outer edge of the Cil webs 15. After assembly the joints on the side opposite the angle members may be covered by a plate 85. As shown at the leftside of Fig. 4, the nested angle members 82 die out at different points vertically. Also, the outer edges of the intermediate bulkheads E, F and G, are strengthened opposite the angle members 82 by plates 86. The sides of the bulkhead unit are covered by skin blankets 81 which continue fore and aft as a body skin blanket. The connections of the skin blankets 81 to the sides of the bulkheads below the wings are reinforced by thin vertical weld strips 88 on the outside of the skin.

Body frame in secondary stress zone As shown in Fig. l2, the body girdle frames 59 in the secondary zone comprise light roof girders or beams 90, outwardly inclined side studs 9|, and curved crown connecting beams 92. The roof skin blanket 1| is a continuation of the roof skin blanket 1| of the primary stress zone and the blanket 81 is a continuation of the side skin blanket of the primary stress Zone. The frame in the secondary stress Zone is made relatively light to permit some bulging near the top whereby the wings will absorb the stresses and thus avoid breakage of the body frame as might occur if it were made too stiff. The beams 02 at the lower end overlap the side studs 9| and are welded thereto. At the upper end the beams 92 are connected to the roof beams 9i! and to the longitudinal members 12, 13 =by cupped gusset clips 93 welded thereto. As shown in Figs. 3 and 9, the lower edges of the beam tl have ceiling stringers 94 secured thereto and at the ends of the heavy stress Zone there are provided angularly disposed members 95.

Body opening for wing anchorage As shown to best advantage in Figs. 3 and 4, the body skin cover 81 is cut away in the bulkhead Zone to form a wing anchorage opening |00 and the upper and outer corners of the bulkheads project through the opening. At the front edge of the opening the skin sheet is reinforced by an angle strip iil welded to the skin; at the rear edge by edge members |02, |03 and |04; and at the lower edge byangle vstrips |05 between the bulkheads. Small gusset plates |0li further reinforce the corners at the bulkheads.

Forward of the wing root opening |00 in the body (Figs. 2 and 3) there is secured a curved angle strip H0 to which there is later attached,

the inner edge of a nose fairing skin sheet To the rear of the opening there is secured an upper angle strip! l2 to which the inner edges of fairing sheets H3, ||4 and ||5 are secured. A lower angle strip H5 extends forward for a distance from the rear end of the upper angle strip ||2 for anchorage of the lower skin sheet connection. Forward of the strip H6 (Fig. 12) where the door opening makes the use of welding tongs convenient the lower wing skin sheet connection may be welded directly to the body skin sheet.

Wing structure The wings are built upon the forward spar 4| and the rear spar 42. As shown in Figs. 15 and 16, the wings further comprise nose rib elements |20, nose skin cover sheet |2|, main rib elements |22, upper skin blanket |23, lower skin blanket |24, trailing section rib elements l 25, and trailing section skin blankets 12b, |21, upper and lower respectively.

The nose rib elements |20 are secured to the forward spar by gusset members |29 and vertical angle members |30.

The main rib elements |22 are formed of overlapped spliced webs |3|d, Ilb stiffened'by overlapped strut ribs |32a, |3217. They are secured to the forward spar by angle members |33 and gussets |34 and to the rear sparr by angle members l and lower skin blankets. i ket, as shown in Figs. Sand 11, a member |12 is Q spliced into theV end of a skin blanket Stringer M2 and extends alongside the bulkhead web 15 past the gusset plate 63 and into the end of a roof beam 6|; It is welded to all of these contiguous members. v

Vstringers |92 adjacent the spars and lighter hatshaped stringers |43 in the intermediate Zone.` Immediately along the spars there are border hat-shaped stringers |44.

The forward spar il includes a web |59, an upper'angle-shaped cap strip or chord 5|, and a lower cap strip |52. Reinforcing strips |53 may also be provided for the upper and lower edges of the web on the side opposite the chords, and vertical web stiieners ribs |54 on the same side as the chords.

The rear Spar i2 includes a web |99, an upper angle-shaped cap strip or chord |6|, and a lower cap strip |62. Reinforcing strips |63 may also be provided for the edges of the web.

Wing-to-bulkhead connection spar is out off at an angle at the inner end to i'lt` adjacent the bulkhead web 15 andv is welded through the overlapping angle 82 and the joint cover plate 85. The upper spar chord runs through alongside the smooth upper side of thel bulkhead web and into the end of the roof beam 2|, overlying the gusset plate 63 at its inner end,

and is welded to these members along its overlapped length as indicated. At the bottom a long angle-shaped member |55 is spliced into the spar shaped member |66 is spliced Within the first. The vertical flanges of both members |55 and 55 are deepened for strength at the meeting line between bulkhead and spar webs. pieces |55, |55 lie alongside the smooth face of the bulkhead web and are welded thereto, as indicated. The inner end of the splicer |65 is joggled at the end to t the ange of the bulkhead chord member 99 and iswelded thereto. In Fig,

The upper skin blanket |23 `4r() with the lower chord |52 and a short ang1e` 7 it .can alsobe observed that the cover strip 85 is joggled on the edges .and that short channel stiffeners |51, |58 are welded to the adjacent bulkhead and spar webs respectively in the joggles to provide greater-strength for a nose rib element which is secured here.

The gussets |29 for the nose rib are shown but the nose rib itself is omitted in Fig. 7.

The rear spar connection is Very Similar to that At the three intermediate bulkheads, E, F and G, the wings are anchored through their upper the latter. Both members or splicels |15, |15 are deepened at the edge of the bulkhead for strength.

In Figs. 17-20 the details of this splice between the members |15, |119 and the blanket Stringer |42 are shown. The stringer is made somewhat shorter than the adjacent Stringers, as at |18, and is slit at the end,jas at |159. Also the bottom flange on one side is cut away for a greater distance, as at |89. The side edge of the adjacent Stringer is cut away, as at ISE, to accommodate the widened base flange of the bottom member |15. Both members |15, |16 underlie the end of the stringer and are welded both to the Stringer and tothe skin sheet. f Y

Referring to Figs. 2l to 24, where the members |15, |16 are rooted in the center o1 themain wing section and the hat-Shaped Stringers |115 are encountered, one is cut away for a considerable distance from the end, as at |83, to accommodate the end of the shorter member Ille and the base flange of the longer member |15 is placed under the end of the Stringer. The members |15, V|19 are welded both to the Stringer |63 and to the skin sheet.

Trailing section anchorage Referring to Figs. 2, 3, 12, 13 and 14 the connections for the trailing edge section or secondary stress Zone are shown. The top and bottom Skin blankets |25, |21 are provided with spanwise extending strut members |81, |88 respectively which are anchored at their outboard ends to the Skin and to the ribs |25.` At their inner ends the strut members are provided with threaded plugs |89 which extend through small holes |99 in the side skin blanket 81 of the body and are anchored in socket brackets I9| which are bolted or otherwise secured to the body frame members 92.

At the rear edge of the trailing section an edging member |92, which secures the converging skin sheets |25, |21 together, projects for a distance to nd anchorage at the junction ofthe angle Strips 2 and IIS on the body and is secured thereto. y

The fairing strips i3, H4 and H5 at the top of the wing are provided with interior reinforcement |93 and are secured to the skin blanket- 4 lower trailing skin blanket, or a suitable fairing At the upper skin blan- At theY lower skin blanket, a long member |15 and a short member |19 are spliced into the end chord member 89, being joggled to accommodate filler piece, is anchored to the body angle piece H5. Forwardly of the angle piece HB the lower skin blanket is provided with an angle piece |91 which is welded to the body skin sheet 81, the door opening C providing access for welding tongs here. This angle piece |91 forms an important longeron for transferring wing torque into the body. An opening in the skin is lclosed by a plate E98 secured by screws or bolts |911.

An added strengthening angle piece |99 (see Fig.

1') extends with the angle piece |91 from the door region up into the primary stress Zone, specifically from about the middle of the door zone to a point just forward of bulkhead G.

Exterior .connection in primary gone As shown in various views, best perhaps in Fig, 5, the upper skin blanket |23 of the main wing section has welded thereto an angle-Shaped piece 299, the upper edge of which is secured as by bolts or screws |99 to the longeron12 (Figs. 8, 11) or to both the longeron 12 and the tie member 1 3 '9j (Figs. 7, 9,'10) After attachment of the angle piece 200, the nose fairing piece and the trailing fairing piece H3, the upper skin |23 is faired to the body by a fairing piece 20| secured by bolts or screws |94.

At the bottom of the wing (Fig. 1), the angle piece |91 extends forward from the trailing section along the main wing section to the nose section, a. reinforcing sheet 202 rbeing disposed at the inner edge of the skin blanket |24, beneath the outwardly extending flange of the, member |91. In the main wing section the lower flange of the angle piece |91 is secured to the body blanket 01 by bolts or screws |94, and forward of thefront spar and bulkhead it is secured by welding. The extension of the body opening forward of the spar` and front bulkhead provides access for welding tongs in this region when the nose fairing piece is not present. Another removable nose closure piece 205 is also provided.

Bullchead walls As shown in Fig. 16, the space between the inner ends of the bulkheads is closed by removable side wall plates 208. The plates are strengthened to resist pressure of cargo material by stringers 209. In most of the other views, these plates are omitted, but they are shown in Figs. 10 and 11.

The bulkhead structure is strengthened by horizontal plates 2| 0 (Fig. 16) secured between bulkheads.

Assembly The assembly procedure may be explained by reference to Fig. 9. The body at the bulkhead unit is assembled in four parts, namely, the two sides with the triangular bulkhead elements and skin blanket, either before or after the wings are secured to the bulkhead sides, the bottom with floor girders and skin blanket, and the roof with roof girders and skin blanket. The sides and bottom are secured together by welding the juxtaposed flanges of longerons 65 together and by welding flat gusset plates (not detailed) to the girder webs and the side webs of the bulkheads. The sides and top are secured together by welding the juxtaposed flanges of the longerons 12 and 13 together and by welding the gussets 63 to the girder webs and the side webs of the bulkheads. The wing anchorage openings |00 leave the top outer corners of the bulkheads exposed for the introduction of the root end of the wing.

As shown in Fig. 2 and at the left of Fig. 9, the wing assembly with the projecting members |65, |12, |81 and |91 is pushed endwise into position and these members secured to the lsides of the bulkhead unit. cured to the bulkhead webs 15 by splice plates 95. The upper angle piece 200 on the upper wing blanket is secured to the body longerons 12, 13 by bolts |94. The lower angle piece |91 on the lower wing blanket is secured to the body by bolts |94 in the middle (at the main wing section) and by welding at the ends, as heretofore described.

Thereafter the fairing pieces lil, |13, H4, H5, |93, 20| and 205 are attached in the manner heretofore described.

Summary It ls thus seen that the invention provides an improved wing-to-body root anchorage, including an improved open-compartment body frame construction to take the necessary stresses, and

Y bend upward under wing loading stresses.

The spar webs |50 are sealso an improved method of assembly.

The advantages of the construction in taking flight stresses have already been noted. It was shown how the cargo loading on the oor girders assisted in resisting the tendency of the girders to Also it was shown how the upward air vacuum pull on the roof girders assisted in resisting the tendency of the girders to bend downward under wind loading stresses. A very rigid wing anchorage is thus effected.

The construction is equally well adapted to withstand landing stresses. This has been partly explained and may be understood more fully by referring to Figs. 36 and 37. Here it may be seen that the motors M are mounted on the leading edge of the wings and outboard from the wing roots in the body. Also that the tricycle landing gear includes two wheels R beneath the motor nacelles N near the rear spar 42 and a single front wheel S beneath the front of the fuselage. The center of gravity is located at C. G.

Assuming that the fully loaded plane is set down heavily on the rear wheels, it can be seen that the body, being suspended b-etween the wheels, tends to bend and shear the wings at their roots to the body. This force acts in a manner similar tothe -in-flight forces and the bulkhead and wing anchorage unit is built strongly to resist it. Also the motors, being heavy and mounted on the leading edge of the wings well in front of the wheels R, tend to shear the wings off at their roots; but the bulkhead unit is built deep vertically and also long in a chordwise direction and is well able to withstand this force. Insofar as this action resultsin lifting the rear edge of the wings it is favorable in resisting the downward action produced bythe unsupported Weight of the tail. It has already been explained that the down swing of the tail tends to crush the body in the region of the door C; that this causes a bulging action in the light stress zone of the body above th-e door; and that the lateral rigidity of the wing skin and frame causes this bulging force to be transferred into the strong bulkhead and wing anchorages in the heavy stress zone of the body and wings. Now it can be seen that the bending stresses on the wing and thetwisting stresses caused by the motor weight also assist in counteracting the body-bulging action caused by the weight of the tail.

Thus by causing normally objectionable forces to act against each other and by designing parts Y to take stresses over and above those for which they are primarily designed, a very light but strong construction is produced. Hence, doors may be provided at selected locations, and instead of being obliged to add heavy parts to the body to strengthen it in the region of the doors, as

commonly required, the wing structure is so designed and disposed as to take the required stresses.y

The construction is convenient to build in subassemblies and easy to assemble into larger units and finally into the complete unit. Also good access is provided forlater installing auxiliary equipment. l

While one embodiment of the invention has been specifically illustrated and described, it is to be understood that .the invention may have various embodiments within the limits of the prior art and the scope of the subjoined claims.

What is claimed is:

1. An aircraft comprising a body and an airframe 'of thebody, means connecting the skin covering of the airfoil to the skin covering of the body, and means, other than the frameto=frame and the coveringeto-covering 'conne-cting means, connecting the skin covering of the sheet and reinforcing stringers therefor, meansv connecting the. frame of the airfoil to ythe frame of the body, means connecting the stringerev of the airfoil tothe frame of the body, and means connecting the Yskin vsheet of the airfoil to the skin covering ofthe body. b

3. An aircraftV comprising a body and an airlfoil each including a frame and a skin covering, the airfo-ilin a central section thereof including spaced spars and the skin covering of the central section of the airfoil including a skinsheet and reinforcing stringers therefor, means connecting the frame of the airfoil. to the frame of the body, means connecting said airfoil stringcrs to the frame of the body, and means connecting the skin covering of the airf'oil to the skin covering of the body.

4. An aircraft comprisinga body and an airfoil each includinga frameand a skin covering. the body frame at the airfoil including a plurality of j transverse girdles, the airfoil frame including a plurality lof spaced spars, andthe airfoil skin covering including reinforcing stringers, means connectingsaid spars to certain ofrsvaid girdles, and means connectingsaid stringers to others or said girdles. l e

vfoil each including a frame and skinv covering, means connecting the frame of the airfoil to thev 5. Anaircraft comprising a body and Wings Y each including a frame and a skin covering, the

body frame attlrie Wing location including a girdle 3 formedl of side bulkheads and transverse girders connecting the ends of the bulkheads to form 'an l interiorcargo' space', the girdle bulkheads each l, beingtriangular in transverse section With a gene erallyhorizontal Abase 'o'f a triangle aligned with oneo said ,girders, and said Wings beingrsei curedvte the llulkheads` adjacent the bases, the

1 inner side di the triangular bulkhead dening the iside of the Vcargo space, and the outerl side of l the bulkhead dening the `outer streamline con'- tour kof the aircraft body,l the bulkheads Within thawing root zone being provided Withvertical i i stiieners and in the zone outside the Wing root l zone vbeing iprovided Vwith Yhorizontal stirfeners.

6. Anaircraft comprising a 7body and Wings 5 each including a'frame and a skin covering, the

body franieat the wing location including a aligned with one of said girders, and said Wings 7, An :aircraft comprising a body' and wings each including a'frame'and a skin covering, the

" girdle formed of side bulkheads and transverse l girders connecting the ends of the bulkheads to 1 forni an interior cargo space,ethe girdle bulkheads each being'triangular in transverse seci tion With a. generally horizontal base of a triangle `top of the girdle, the inner side of the triangular bulkhead being substantially vertical and dening the side of the cargo space, and the outer side vof the bulkhead being inclined inv/ard from top to bottom and dening theY outer streamline contour of the aircraft body, the( bulkheads Within thawing root zone being provided-Withfvertical stifieners and in the zone outsideV the Wing root zonebeing provided with'horizontal stiiieners.

8. An `aircraft comprising a'body and YWings each including a frame and a skin covering, the body frame at the Wing Ylocation inciuding a girdle formed of side bulkheads and transverse girders connecting the ends of the bulkheads to form an interior cargo space', the girdle bulkheads each being triangular in transverse section with a generally horizontal base of aV triangle aligned with one of said girders, and said Wings being secured to the bulkheads adjacent the bases, said Wings each including vertically spaced skin coverings, one of which extends across the base of the triangular bulkhead and onefoi which stops against the outer side of the bulkhead, the inner side of the triangular bulkhead defining the side of the cargo space, and the outer side of the bulkhead defining the outer streamline contour of the aircraft body, the bulkheads within the Wing root zone being provided with vertical stiffeners and in the zoneoutside the Wing root zone being provided with horizontal stifeners.

9. An aircraft comprising a body and wings each including a frame and a skin covering, the body frame at the wing location including a girdle formed of side bulkheads and transverse girders connecting the ends of the bulkheads to form an interior cargo space, the girdle bulkheads each being triangular in transverse section with a generally horizontal base of a triangle aligned with one of said girders, Yand saidvvings being secured to the bulkheadsk Vadjacent the bases, said Wings each including vertically spaced shear elements disposed alongside a bulkhead and means securing said elements in shear to the bulkhead, the inner side of the triangular bulkhead deining the side ofthe cargo space, and the outer side cf the bulkhead defining the out-er streamline contour of the aircraftbody, the'bulkheads Within the wing root zone being provided with vertical stiieners and in the zone outside the Wing .root zone being provided with horizontal stiffeners.

i0. An aircraft comprising a body and Wings each including a frame and a skin covering, the Y Y form an interior cargo space, the girdle bulk' Y heads each being triangular in transverse section With a generally horizontal base oi' a triangle aligned with one of said girders, and said Wings being secured to the bulkheads adjacent the bases, said Wings including vertically spaced splice members secured by shearrneans to the bulkhead, ,one of said splice members extending entirely across the base of the bulkhead and be-4 

